Fixes from Trevor's comments, and some other comment improvements

Fixes for trevor's comments from https://github.com/freedomjs/freedom-for-chrome/pull/13 

TESTED with: grunt test, all tests pass.
(But note: integration test times out, but doesn't seem to report any errors; seems to do it on master too, I've filed a bug: https://github.com/freedomjs/freedom-for-chrome/issues/15 )

Also: Travis CI seems not to run the integration tests (I guess we don't have selenium for Travis).
typo: Resolves Freedom's promise for |this.listen|.